Rate-constrained relaying: achievable rates and protocol comparisons

In this paper, the impact of limited resources on achievable rates in relay channels is investigated. Resource limitation is modeled (as previously proposed) by (Rmacr) which constrains the rate at which a relay can reliably decode or encode data. With this constraint in hand, the achievable rates for two commonly studied protocols, decode-and-forward and estimate-and-forward are derived and_compared. In particular, the case of severe resource limitation (Rmacr rarr 0) is considered. While decode-and-forward is the superior protocol for most relay locations (topologies) under no rate constraints, estimate-and forward almost always offers superior performance when relaying with strong rate constraints